WASHINGTON — President Barack Obama this morning called North Korea’s latest nuclear test a “highly provocative act” that threatens U.S. security and international peace. “The danger posed by North Korea’s threatening activities warrants further swift and credible action by the international community,” Obama said in a statement issued early today. “The United States will also continue to take steps necessary to defend ourselves and our allies.” North Korea said it successfully detonated a miniaturized nuclear device today at a northeastern test site. South Korean, U.S. and Japanese seismic monitoring agencies said they detected an earthquake in North Korea with a magnitude between 4.9 and 5.2. North Korea’s official Korean Central News Agency said the test was conducted safely but with “great explosive power.” It said the test is aimed at coping with “ferocious” U.S. hostility that undermines the North’s peaceful, sovereign right to launch satellites. Last month, North Korea’s National Defense Commission said the United States was its prime target for a nuclear test and long-range rocket launches.